JP2008032912A - Method of manufacturing microlens - Google Patents

Method of manufacturing microlens Download PDF

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JP2008032912A
JP2008032912A JP2006204782A JP2006204782A JP2008032912A JP 2008032912 A JP2008032912 A JP 2008032912A JP 2006204782 A JP2006204782 A JP 2006204782A JP 2006204782 A JP2006204782 A JP 2006204782A JP 2008032912 A JP2008032912 A JP 2008032912A
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Japan
Prior art keywords
microlens
exposure
mask
deformation
forming
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JP2006204782A
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Japanese (ja)
Inventor
Masaaki Kurihara
Katsutoshi Suzuki
栗原  正彰
勝敏 鈴木
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Dainippon Printing Co Ltd
大日本印刷株式会社
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Priority to JP2006204782A priority Critical patent/JP2008032912A/en
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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B3/00Simple or compound lenses
    • G02B3/0006Arrays
    • G02B3/0012Arrays characterised by the manufacturing method
    • G02B3/0018Reflow, i.e. characterized by the step of melting microstructures to form curved surfaces, e.g. manufacturing of moulds and surfaces for transfer etching
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/0005Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20Exposure; Apparatus therefor
    • G03F7/2022Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a microlens for forming the microlens whose shape is smooth in a simple method by possessing a shape in which the maximum film thickness position is different from a gravity position. <P>SOLUTION: The method of manufacturing the microlens has: a basic shape formation exposure process for performing exposure by using a mask for forming microlens basic shape to a photosensitive resin layer formed on a substrate; and a deformation exposure process for performing exposure having a unit cell exposure profile different from exposure during the basic shape formation exposure process by using the mask for microlens deformation to the photosensitive resin layer. The microlens in which the maximum film thickness position is different from the center of gravity is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a microlens that can form a microlens having a shape having a maximum film thickness position different from the position of the center of gravity and having a smooth shape by a simple method.

  The body of a digital camera that has been rapidly spreading in recent years incorporates a solid-state image sensor such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor that records an image by converting subject light into an optical signal. It is. In general, such a solid-state image pickup device receives a subject light and converts it into a photoelectric signal, a color filter formed on the light receiving device, and a light collecting element for improving a light collection rate. And a microlens.

  The microlens is very useful from the viewpoint of improving the light collection rate to the light receiving element, but on the other hand, there are cases where problems such as noise and shading become conspicuous due to the installation of the microlens. Specifically, when oblique light is incident on the microlens, the light is not sufficiently collected on the light receiving element compared to when light is incident on the microlens from the vertical direction. There is a case where a difference occurs in the degree, which appears as a difference in signal output, and generates noise due to output variation. In addition, for example, oblique light causes a difference in signal output between the pixel central portion of each pixel region and its peripheral portion, and the signal output in the peripheral portion may be lower than that in the pixel central portion. The output difference sometimes causes shading on the output screen of the image.

  In addition, for the purpose of high integration and the like, an image sensor configured to share one signal readout circuit among a plurality of light receiving elements, that is, an image sensor having a so-called multiple pixel sharing structure is known. In the image pickup device, the center position of the microlens and the center position of the light receiving device may not match in plan view due to restrictions on the configuration, and similarly, problems such as noise and shading have occurred.

  For such problems, it has been proposed to use a microlens having a non-rotationally symmetric shape instead of the conventional rotationally symmetric shape. That is, by using a non-rotationally symmetric microlens, it is an attempt to make light collection on the light receiving element uniform and suppress problems such as noise and shading.

  In Patent Document 1, a microlens having a non-rotationally symmetric shape is formed by forming an asymmetric lattice-like pattern at the center of a unit cell, applying and patterning a lens material, and then performing heat flow. A method has been proposed. However, in Patent Document 1, since a microlens is formed by heat flow, it is difficult to accurately form a desired lens shape.

  On the other hand, Patent Document 2 proposes a method of forming a microlens having a desired lens shape by double exposure using a gradation mask and a correction aperture mask. However, the non-rotationally symmetric microlens is not particularly described.

JP 2002-76315 A JP 2005-258349 A

  The present invention has been made in view of the above problems, and a microlens having a shape in which the maximum film thickness position is different from the position of the center of gravity and having a smooth shape can be formed by a simple method. The main object is to provide a method of manufacturing a lens.

  In order to solve the above-described problems, in the present invention, a basic shape forming exposure step in which a photosensitive resin layer formed on a substrate is exposed using a microlens basic shape forming mask, and the photosensitive property described above. A deformation exposure step for performing exposure having a unit cell exposure profile different from the exposure in the exposure step for forming the basic shape using a microlens deformation mask for the resin layer, and having a maximum film thickness position Forming a microlens different from the center of gravity position.

  According to the present invention, by performing exposure twice with different unit cell exposure profiles, a microlens whose maximum film thickness position is different from the center of gravity position can be easily formed.

  In the above invention, the microlens basic shape forming mask is preferably a gradation mask having a transmittance distribution which is rotationally symmetric with respect to the center position of the unit cell. This is because such a gradation mask is excellent in versatility.

  Moreover, in the said invention, it is preferable that the said mask for micro lens deformation | transformation is a mask provided with the opening part which does not have gradation, and the exposure in the said exposure process for deformation | transformation is a defocus exposure. This is because a mask having an opening having no gradation is easy to manufacture, and a microlens having a smooth shape can be obtained by performing defocus exposure.

  In the present invention, there is an effect that a microlens having a shape in which the maximum film thickness position is different from the position of the center of gravity and having a smooth shape can be formed by a simple method.

  Hereinafter, the manufacturing method of the microlens of this invention is demonstrated.

  The microlens manufacturing method of the present invention includes a basic shape forming exposure step in which a photosensitive resin layer formed on a substrate is exposed using a microlens basic shape forming mask, and the photosensitive resin layer is formed on the photosensitive resin layer. On the other hand, using a microlens deformation mask, and a deformation exposure process for performing exposure having a unit cell exposure profile different from the exposure in the exposure process for forming the basic shape, the maximum film thickness position is the center of gravity position And a different microlens is formed.

In the present invention, the “maximum film thickness position” refers to a position where the film thickness of the microlens is maximized. The “center of gravity position” refers to a position that is the center of gravity of the contact surface where the microlens contacts the substrate. The maximum film thickness position is different from the center-of-gravity position microlens, for example, as shown in FIG. 1 (a), refers to the maximum thickness position P M is different from the center-of-gravity position P G. In the conventional microlens, for example, as shown in FIG. 1B, the maximum film thickness position P M coincides with the gravity center position P G.

  According to the present invention, by performing exposure twice with different unit cell exposure profiles, a microlens whose maximum film thickness position is different from the center of gravity position can be easily formed. In addition, by forming a microlens whose maximum film thickness position is different from the position of the center of gravity, it is possible to obtain a solid-state imaging device or the like in which the above-described noise and shading are suppressed. Furthermore, since the microlens manufacturing method of the present invention is usually a method of controlling the shape of the microlens by the exposure process, the microlens is formed with higher accuracy than the conventional method of forming the microlens by heat flow. can do.

  Moreover, the manufacturing method of the microlens of this invention can be divided roughly into the following two aspects by the order which performs the exposure process for basic shape formation, and the exposure process for deformation | transformation. That is, an aspect (first aspect) of performing an exposure process for forming a basic shape and then performing an exposure process for deformation, an aspect of performing an exposure process for deformation and then performing an exposure process for forming a basic shape (second aspect), Can be broadly classified. Hereinafter, description will be made for each aspect.

1. First Aspect First, a first aspect of the microlens manufacturing method of the present invention will be described. The manufacturing method of the microlens of this aspect performs a basic shape forming exposure process first, and then performs a deformation exposure process. That is, the microlens manufacturing method according to this aspect includes a basic shape forming exposure step in which a photosensitive resin layer formed on a substrate is exposed using a microlens basic shape forming mask, and the basic shape formation described above. A deformation exposure step of performing exposure having a unit cell exposure profile different from the exposure in the basic shape forming exposure step, using a microlens deformation mask for the photosensitive resin layer after the exposure step for And a microlens having a maximum film thickness position different from the center-of-gravity position is formed.

  Next, the manufacturing method of the microlens of this aspect is demonstrated using drawing. FIG. 2 is a process diagram showing an example of a method for manufacturing the microlens of this embodiment. The microlens manufacturing method shown in FIG. 2 includes a photosensitive resin layer forming step in which a positive photosensitive resin layer 2 is formed on a substrate 1 as shown in FIG. As shown in the drawing, a basic shape formation is performed by using a gradation mask having a transmittance distribution rotationally symmetric with respect to the center position of the unit cell as the microlens basic shape forming mask 3, and performing exposure to form the basic shape of the microlens. 2C, and a deformation exposure process for partially exposing the photosensitive resin layer 2 using the microlens deformation mask 4 as shown in FIG. 2C. Furthermore, by performing a developing process, as shown in FIG. 2D, a microlens 5 having a maximum film thickness position different from the center of gravity position can be obtained.

  FIG. 3 is an explanatory diagram for explaining a mask and an exposure profile used in the method for manufacturing the microlens shown in FIG. FIG. 3A is a schematic plan view of the microlens basic shape forming mask 3 shown in FIG. 2B, and shows a gradation mask having a transmittance distribution rotationally symmetric with respect to the center position of the unit cell. ing. Specifically, it is a gradation mask for a positive photosensitive resin layer that has a higher light shielding property toward the center position of the unit cell. FIG. 3B shows an exposure profile of the AA ′ cross section of FIG. FIG. 3B shows a unit cell exposure profile of the unit cell α in the basic shape forming exposure step as an example of the unit cell exposure profile.

  On the other hand, FIG. 3C is a schematic plan view of the microlens deforming mask 4 shown in FIG. 2C and shows a mask having a rectangular opening 6. FIG. 3D shows an exposure profile of the AA ′ cross section of FIG. However, FIG. 3D shows an exposure profile when defocus exposure described later is performed. FIG. 3D shows a unit cell exposure profile of the unit cell α in the deformation exposure process as an example of the unit cell exposure profile. As can be seen by comparing FIG. 3B and FIG. 3D, in this embodiment, two exposures with different unit cell exposure profiles are performed. As a result, as shown in FIG. 3E, the unit cell exposure profile superposition is non-rotationally symmetric with respect to the center position (center line X) of the unit cell. As a result, as shown in FIG. 3F, a microlens 5 having a maximum film thickness position different from the gravity center position can be obtained. The “unit cell” refers to a unit area on a substrate on which individual microlenses are formed, and is usually a square. The “center position of the unit cell” refers to a position that is an intersection of the diagonal lines of the unit cell.

  In addition, the microlens manufacturing method of this aspect generally includes a photosensitive resin layer forming step for forming a photosensitive resin layer on a substrate, a basic shape forming exposure step, a deformation exposure step, and a development step. Have Hereinafter, each step will be described.

(1) Photosensitive resin layer formation process First, the photosensitive resin layer formation process in this aspect is demonstrated. The photosensitive resin layer forming step is a step of forming a photosensitive resin layer on the substrate. The photosensitive resin layer is a layer that becomes a microlens by performing an exposure process and a development process described later.

  As said board | substrate, although it changes with uses etc. of a micro lens, transparent glass substrates, such as quartz glass, an alkali free glass, lead glass (blue plate glass), etc. can be mentioned, for example. Further, as the substrate, a solid-state image sensor (material for a solid-state image sensor) before forming a microlens can be used. For example, a solid-state imaging device can be obtained by forming a microlens on a planarization layer that constitutes a solid-state imaging device material.

  In addition, as the photosensitive resin constituting the photosensitive resin layer, either a positive photosensitive resin or a negative photosensitive resin can be used, and among them, a positive photosensitive resin is preferable. Examples of the positive photosensitive resin include phenol epoxy resin, acrylic resin, polyimide, cycloolefin, and the like. Specific examples include MFR401 (manufactured by JSR Corporation), T-HMR P11 (manufactured by Tokyo Ohka Kogyo Co., Ltd.), and the like. On the other hand, examples of the negative photosensitive resin include an acrylic resin. Specifically, PAK-01 (made by Toa Gosei Co., Ltd.), NIP-K (made by Zen Photonics), etc. can be mentioned.

The method for forming the photosensitive resin layer on the substrate is not particularly limited, and specific examples include a spin coating method.
Further, the thickness of the photosensitive resin layer varies depending on the use of the microlens and the like, but is usually in the range of 0.1 μm to 100 μm.

(2) Basic shape forming exposure step Next, the basic shape forming exposure step in this embodiment will be described. The basic shape forming exposure step is a step of exposing the above-described photosensitive resin layer using a microlens basic shape forming mask.

  The microlens basic shape forming mask used in this embodiment is not particularly limited as long as a desired microlens can be obtained by combination with a microlens deformation mask described later. Specifically, a gradation mask (rotationally symmetric gradation mask) having a transmittance distribution that is rotationally symmetric with respect to the center position of the unit cell can be used.

  The rotationally symmetric gradation mask is usually used for a positive photosensitive resin layer (sometimes simply referred to as “positive type”) or a negative photosensitive resin layer (depending on the type of the photosensitive resin layer described above). Is simply referred to as “for negative type”). FIG. 4A is a schematic plan view showing an example of a positive type rotationally symmetric gradation mask. This rotationally symmetric gradation mask has a higher light shielding property toward the center of the unit cell. Since the positive photosensitive resin layer is decomposed by exposure, the basic shape of the microlens can be formed by using the gradation mask as described above. FIG. 4B shows an exposure profile of the AA ′ cross section of FIG.

  On the other hand, FIG. 4C is a schematic plan view showing an example of a negative-type rotationally symmetric gradation mask. This rotationally symmetric gradation mask has a lower light shielding property toward the center of the unit cell. Since the negative photosensitive resin layer is cured by exposure, the basic shape of the microlens can be formed by using the gradation mask as described above. FIG. 4D shows an exposure profile of the AA ′ cross section of FIG.

  The light used for exposure is not particularly limited as long as it can decompose the positive photosensitive resin layer, or can cure the negative photosensitive resin layer, and is not particularly limited. The same light as that used for exposing the light can be used. For example, g-line (436 nm) and i-line (365 nm) of a mercury lamp, KrF excimer laser (248 nm), ArF excimer laser (193 nm), and the like can be mentioned.

  Moreover, in this aspect, two exposure processes, the basic shape forming exposure process and the deformation exposure process, are performed. The ratio of the exposure amount in the basic shape forming exposure step and the exposure amount in the deformation exposure step varies depending on the type of mask and resist used, but for example, the exposure for forming the basic shape When the exposure amount in the process is 100, the exposure amount in the deformation exposure step is preferably in the range of 50 to 100, and more preferably in the range of 70 to 80.

Further, as the exposure amount in the basic shape for forming exposure step, it is not particularly limited, for example, 50mJ / cm 2 ~100mJ / cm 2 in the range, among them of 65mJ / cm 2 ~75mJ / cm 2 It is preferable to be within the range.

Further, the total of the exposure amount in the basic shape forming exposure step and the exposure amount in the deformation exposure step varies depending on the type of the mask to be used, for example, 100 mJ / cm 2 to 150 mJ / in the range of cm 2, and preferably in the range of these the 115mJ / cm 2 ~135mJ / cm 2 .

(3) Deformation exposure step Next, the deformation exposure step in this embodiment will be described. The exposure process for deformation in this aspect uses a microlens deformation mask for the photosensitive resin layer after the exposure process for forming the basic shape described above, and is a unit different from the exposure in the exposure process for forming the basic shape described above. This is a step of performing exposure having a cell exposure profile.

  In the present embodiment, the “unit cell exposure profile” indicates the distribution of light intensity in the unit cell. In addition, “exposure having a unit cell exposure profile different from the exposure in the basic shape forming exposure step” means a unit cell exposure profile having a shape different from the unit cell exposure profile in the basic shape forming exposure step. The exposure that has the relationship that the superposition of the unit cell exposure profiles in the exposure process for forming the basic shape and the exposure process for deformation does not have a rotational symmetry with respect to the center position of the unit cell. Specifically, as shown in FIG. 3B and FIG. 3D described above, the unit cell exposure profiles of the unit cells α are different from each other. Further, as shown in FIG. The exposure that causes the unit cell exposure profile of the cell α to be supersymmetric with respect to the center position (center line X) of the unit cell.

  The microlens deformation mask used in this embodiment is not particularly limited as long as it can perform exposure having a unit cell exposure profile different from the exposure in the exposure process for forming the basic shape. .

  In particular, in this embodiment, it is preferable to select a positive or negative type microlens deformation mask depending on the type of the photosensitive resin layer described above.

A positive type microlens deforming mask usually has an opening at a position where the positive type photosensitive resin layer is to be further decomposed.
Examples of the shape of the opening include a rectangular shape, a polygonal shape, a circular shape, and an elliptical shape. Among them, the rectangular shape is preferable. In addition, the position of the said opening part will not be specifically limited if the exposure which has a unit cell exposure profile different from the exposure in the exposure process for basic shape formation can be performed.

  The positive type microlens deforming mask may be one in which an opening is formed for each unit cell, or may be one in which an opening is formed over a plurality of unit cells. As a positive type microlens deforming mask in which an opening is formed for each unit cell, specifically, each unit cell 7 has an opening 6 as shown in FIG. Etc. The unit cell 7 may have a plurality of openings 6. Further, as a positive type microlens deforming mask in which openings are formed over a plurality of unit cells, specifically, as shown in FIG. 5 (b), the openings 6 are formed over a plurality of unit cells 7. And the like.

  In addition, the positive type microlens deformation mask may be a mask having an opening having gradation or a mask having an opening having no gradation. In the aspect, the mask is preferably provided with an opening having no gradation. This is because such a microlens deformation mask is easy to manufacture.

  Furthermore, in this aspect, when the positive type microlens deformation mask is a mask having an opening having no gradation, it is preferable that the exposure in the deformation exposure step is defocus exposure. . This is because a microlens having a smooth shape can be obtained. In this embodiment, “defocus exposure” means that exposure is performed with the focus shifted, and thereby a smooth exposure profile can be provided. Specifically, as shown in FIG. 6A, when the positive microlens deformation mask 4 includes a rectangular opening 6 having no gradation, defocus exposure is performed. Thus, as shown in FIG. 6B, the unit cell exposure profile of the unit cell α becomes smooth. On the other hand, when the defocus exposure is not performed, the unit cell exposure profile of the unit cell α is stepped as shown in FIG.

  Further, the defocus amount at the time of the defocus exposure is not particularly limited, but is preferably in the range of 5 μm to 15 μm, and more preferably in the range of 7 μm to 12 μm.

  As a positive type microlens deforming mask having an opening having no gradation, in addition to the mask shown in FIG. 6A, for example, as shown in FIG. For example, a rectangular opening 6 having no property is formed over a plurality of unit cells 7. Note that a positive photosensitive resin layer is formed on the substrate, an exposure process for forming a basic shape is performed using the rotationally symmetric gradation mask shown in FIG. 4A, and the micro-pattern shown in FIG. The microlens 5 shown in FIG. 7B can be formed by performing a deformation exposure process in which defocus exposure is performed using the lens deformation mask.

  In addition, when a positive type microlens deforming mask having an opening having gradation is used, the same effect as the above defocus exposure can be obtained by performing normal exposure. As a positive type microlens deforming mask having an opening having gradation, for example, a rectangular opening 6 having gradation is formed over a plurality of unit cells 7 as shown in FIG. Can be mentioned.

  On the other hand, a negative type microlens deforming mask usually has a light shielding part at a position where the negative type photosensitive resin layer is not desired to be further cured. Note that the shape and the like of the light shielding portion are the same as those described for the opening of the positive type microlens deformation mask described above, and thus the description thereof is omitted here. In addition, the region (transmission portion) other than the light shielding portion may have gradation properties or may not have gradation properties. Since these descriptions are also the same as the description of the opening portion of the positive type microlens deformation mask described above, description thereof is omitted here.

  Moreover, as the light used at the time of exposure, the same light as that used in the above-described exposure process for forming a basic shape can be used, and thus description thereof is omitted here.

  Further, in this embodiment, at least two exposure steps, that is, a basic shape forming exposure step and a deformation exposure step, are performed. However, an exposure step for finely adjusting the microlens shape may be performed. good.

(4) Development Step Next, the development step in this embodiment will be described. The developing step in this embodiment is a step of developing the photosensitive resin layer with a developer after the above-described deformation exposure.

  The developer used in this embodiment is not particularly limited, and is preferably selected as appropriate according to the type of the photosensitive resin layer used. Specific examples include an alkali developer and an organic solvent developer.

  In this embodiment, the method for developing the photosensitive resin layer is not particularly limited, and examples thereof include an immersion method, a spray method, and a paddle method, and the paddle method is preferable.

(5) Microlens Next, the microlens obtained by the manufacturing method of this aspect will be described. The microlens obtained by this aspect is not particularly limited as long as the maximum film thickness position is different from the center of gravity position, but specifically, the maximum film thickness position of the microlens is the diameter of the microlens. On the other hand, it is preferably 2% or more, more preferably 5% or more away from the center of gravity. This is because it is possible to obtain a solid-state imaging device or the like with good light collection efficiency. The “diameter of the micro lens” refers to the length of the unit cell in the diagonal direction. The diameter of the microlens is preferably 10 μm or less, for example.

  The microlens preferably has no gap between adjacent microlenses. This is because the light collection efficiency can be improved.

  The maximum film thickness of the microlens varies depending on the pixel size, the shape of the microlens, the distance between the microlens and the light receiving element, and specifically, within the range of 0.2 μm to 1.5 μm. Preferably there is.

  The type of the micro lens is not particularly limited, and examples thereof include a spherical type and a refractive index distribution type.

2. Second Aspect Next, a second aspect of the microlens manufacturing method of the present invention will be described. The manufacturing method of the microlens of this aspect performs the exposure process for a deformation | transformation first, and then performs the exposure process for basic shape formation. That is, the microlens manufacturing method of this aspect uses a microlens deformation mask for the photosensitive resin layer formed on the substrate, and is different from the exposure in the basic shape forming exposure process described later. A deformation exposure process for performing exposure with an exposure profile, and a basic shape forming exposure process for performing exposure using a microlens basic shape formation mask on the photosensitive resin layer after the deformation exposure process. In addition, a microlens having a maximum film thickness position different from the gravity center position is formed.

  Next, the manufacturing method of the microlens of this aspect is demonstrated using drawing. FIG. 9 is a process diagram showing an example of a method for manufacturing the microlens of this embodiment. The microlens manufacturing method shown in FIG. 9 includes a photosensitive resin layer forming step in which a positive photosensitive resin layer 2 is formed on a substrate 1 as shown in FIG. As shown in FIG. 9, a deformation exposure process for partially exposing the photosensitive resin layer 2 using the microlens deformation mask 4, and for forming a microlens basic shape as shown in FIG. And a basic shape forming exposure step of performing exposure using a gradation mask having a transmittance distribution rotationally symmetric with respect to the center position of the unit cell as the mask 3. Furthermore, by performing a developing process, as shown in FIG. 9D, a microlens 5 having a maximum film thickness position different from the center of gravity position can be obtained.

  In addition, the microlens manufacturing method of the present aspect usually includes a photosensitive resin layer forming step of forming a photosensitive resin layer on a substrate, a deformation exposure step, a basic shape forming exposure step, and a development step. However, since these steps are the same as those described in the first embodiment, description thereof is omitted here. Further, since the characteristics and the like of the obtained microlens are the same as those in the first aspect, description thereof is omitted here.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the technical idea described in the claims of the present invention has substantially the same configuration and exhibits the same function and effect regardless of the case. It is included in the technical scope of the invention.

Hereinafter, the present invention will be described more specifically with reference to examples.
[Example]
Examples will be described by taking a case where a positive resist is used as a photosensitive resin.
First, a phenol epoxy positive resist was applied by spin coating so that the film thickness was about 1.0 μm, and dried under appropriate conditions.
Next, exposure for forming a basic shape was performed. A unit cell pattern of a photomask used for exposure is shown in FIG. Reference numeral 6 denotes a light shielding portion, and 8 denotes an opening portion, and the transmittance distribution is controlled to be rotationally symmetric by the arrangement of fine dot patterns that are not resolved at the exposure wavelength. The exposure was performed using an I-line stepper with an exposure amount of about 100 mJ / cm 2 and a defocus amount of about 0 μm.
Next, deformation exposure was performed. The exposure was performed using a photomask pattern having one opening 6 for the four unit cells 7 as shown in FIG. The exposure amount was about 50 mJ / cm 2 and the defocus amount was about 10 μm. By performing the first exposure step (exposure for forming the basic shape) and the second exposure step (exposure for deformation), a non-rotationally symmetric exposure profile as shown in FIG. 3E was obtained.
Next, development was performed under appropriate conditions to obtain a microlens having an asymmetric shape. FIG. 11 shows an AFM observation image of the manufactured microlens. 11A is a top view, and FIG. 11B is an AA ′ cross-sectional profile of FIG. 11A. P M and P G not match, it is seen that and has a smooth shape.
As a result, the microlens forming method devised in the present invention can form a microlens having a maximum film thickness position different from the center of gravity position and a smooth shape by a simple method. It could be confirmed.

It is explanatory drawing explaining the shape of a micro lens. It is process drawing which shows an example of the manufacturing method of the micro lens of this invention. It is explanatory drawing explaining the mask used for the manufacturing method of the microlens shown in FIG. 2, and an exposure profile. It is explanatory drawing explaining a rotationally symmetric gradation mask. It is explanatory drawing explaining the mask for positive type microlens deformation | transformation. It is explanatory drawing explaining a defocus exposure. It is explanatory drawing which illustrates the positive type micro lens deformation | transformation mask whose opening part does not have gradation. It is explanatory drawing which illustrates the positive type micro lens deformation | transformation mask whose opening part has gradation. It is process drawing which shows the other example of the manufacturing method of the micro lens of this invention. It is a figure of the gradation mask used in the Example. It is an AFM observation image of the microlens produced in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Photosensitive resin layer 3 ... Microlens basic shape formation mask 4 ... Microlens deformation mask 5 ... Microlens 6 ... Opening 7 ... Unit cell 8 ... Light-shielding part

Claims (3)

  1. An exposure process for forming a basic shape for exposing the photosensitive resin layer formed on the substrate using a microlens basic shape forming mask;
    A deformation exposure process for performing exposure having a unit cell exposure profile different from the exposure in the exposure process for forming the basic shape, using a microlens deformation mask for the photosensitive resin layer,
    And forming a microlens having a maximum film thickness position different from the center of gravity position.
  2.   2. The method of manufacturing a microlens according to claim 1, wherein the microlens basic shape forming mask is a gradation mask having a transmittance distribution which is rotationally symmetric with respect to the center position of the unit cell.
  3.   The said microlens deformation | transformation mask is a mask provided with the opening part which does not have gradation, The exposure in the said exposure process for a deformation | transformation is defocus exposure, The Claim 1 or Claim 2 characterized by the above-mentioned. Microlens manufacturing method.
JP2006204782A 2006-07-27 2006-07-27 Method of manufacturing microlens Pending JP2008032912A (en)

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TW200813485A (en) 2008-03-16

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